Preserved wood and process of preparing same.



PATENTED MAR. 29,. 1904.

I. P. LIHME. PRESERVED WOOD AND PROCESS OF PREPARING SAME.

APPLICATION FILED JUNE 7. 1902.

N0 MODEL.

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No. 756,173. r Patented March 29, 1904.

UNITED STATES PATENT OFFICE.

QIENS P. LIHME, 'OF CLEVELAND, OHIO, ASSIGNO R TO THE GRASSELLI CHEMICALCOMPANY, OF CLEVELAND, OHIO, A CORPORATION. OF

OHIO.

PRESERVED WOOD AND PRocEss OF PREPARING. SAME.

SPECIFICATION forming part of Letters Patent No. 756,173, dated Marci 129, 1904.

Application filed June 7,1902. Serial No. 110,623. (No specimens.)

T all h it y COW/067"": first-named salt, constituting an excellent pre-Be it known that I, TENS P. LIHME, a citizen servative, while theexterior portion of said of the United States of America, and a residentwood contains in its pores a superficial crust 0 of Cleveland, in thecounty of Cuyahoga and of varying depth, composed of silicate of zinc,

5 State of Ohio, have invented certain new and which is both insolubleand fireproof and useful Improvements in PreservedWood and closes in thesoluble chlorid contained in the Processes of Preparing Same, (Case No.3,) of interior of the wood. which the following is a specification. Myinventionmay be more readily explained My invention relates toimprovements in by referring to the accompanying drawings, I0 preservedwoodand process of preparingsame, wherein and has for its object theproduction of wood Figure 1 illustrates in somewhat diagramadapted towithstand moisture, heat, the at- 'matic-manner apparatus adapted forpractictacks of insects, and, in short, to render the ing my invention,and Fig. 2 shows in crosstreated wood as nearly impervious andunafsection a log or railroad-tie and a board after 5 fected by theelements as possible. their treatment in accordance with my im- Zincchlorid has long been recognized as an proved process. extremelyefficient if not the best wood pre- In practicing my process ahermeticallyservative known; but this has been coupled closed chamber isrequired, preferably of such 5 with the distinct disadvantage of thechemcapacity that a large charge of wood may be icals being quitereadily dissolved from the readily inserted for treatment and easilyre-- pores of the impregnated wood when exposed moved therefrom. I tothe-action of the airand rain, thus leaving In the drawings I haveindicated a large the wood entirely unprotected. It hasaccordchamber a,capable of being securely sealed 7 ingly ranked heretofore as atemporary preby a door 6 after the car a, carrying the wood 5 servative.The silicates, notably that of 'so-. 0? to be treated, has been pushedwithin the dium, have likewise been resorted tofor the chamber. Beneaththe rails are shown steampurpose of fireproofing wood and have beencoils e for inducing a high temperature withproven extremely efficient;but are open to the inthe treating-chamber. A vacuum-pumpf, sameobjection just mentioned. My present with its gage f, and a fluid-pumpg, with its 3 invention accordingly proceeds with the idea correspondingpressure-gage g, are connected of combining the advantages of each ofthese with the said chamber a. Apr'essure-equalizer two extremelyeflicient wood preserving It also is associated with the said chamber,the agents, while attaining practical permanence same having a movableweighted head it, in the preservative eifect secured. adapted to beraised in its cylinder upon the 3S Adverting briefly to my improvedprocess increase in the pressure within the chamber and product, I maystate, as introductory to beyond a given point. Upon introducing the amore extended description thereof, that the wood within the chamber itis first subjected process preferably consists in first effecting to adry heat of about 200 by admitting steam 5 approximately the completefilling of the .to the coils e, which heating is continued un- 4 poresor saturation of the treated wood with til the wood has becomethoroughly dried. a solution of zinc chlorid and thereafter sub- Thevacuum-pump f is then put in operation jecting the same to the action ofa silicate sountil the gage f remains substantially conlution, as sodiumsilicate, the useof vacuum stant. The valves c" 70 in pipes 71 k arethen 9 and pressure being resorted to in order to obopened, the latterpipe connecting with the 45 tain the desired impregnation. Under thistank containingazinc-chlorid solution,where+ treatment it will be foundthat the body of the upon the treating-chamber is flooded with the woodis thoroughly impregnated with the said solution of zinc chlorid. Valve11 is then closed and pump g is set in operation and a pressure ofapproximately two hundred pounds to the square inch is secured, whichpressure is maintained ordinarily for five or six hours. -It may be wellhere to observe that the details of the treating process or operationvary considerably, depending upon the kind and condition of the woodunder treatment, so that only general statements can be made which areapplicable to average circumstances. This high pressure is continueduntil the wood has become thoroughly impregnated with the Zinc chlorid,this operation being greatly facilitated by the previous exhaustion ofthe air, after which the solution is pumped out of the chamber and intothe containing-tank. (Not shown in the drawings.) Valve Z1 is thereuponclosed and valve Z is opened to permit the solution of sodium silicateto be pumped through pipeZ into the treating-chamber. As before, thesolution is maintained under a high pressure until the desiredimpregnation with silicate takes place. Treatment under two hundredpounds pressure for five or six hours will commonly suffice. By reasonof the previous impregnation, however, it will be found that theformation of zinc silicate in the exterior portions of the wood throughthe combination of the two salts will clog or check the reaction moreand more and cause the formation of an impervious layer or superficialcrust within the pores of the wood. Depending again upon the kind ofwood and conditions of treatment, this layer will be of greater or lessthicknesssay, from one-eighth to three-quarters of an inch-but will befound sufficient to permeate the wood to form an effective exteriorprotection therefor. After withdrawing the silicate solution from thechamber steam may be admitted to the coils toeifect the rapid drying ofthe treated wood or the car may be removed from the chamber, permittingits recharging while the treated wood is allowed to dry naturally beforemaking use of it.

It is scarcely necessary to state that proper precautions should betaken to insure the free access of the separate solutions to all of thewood under treatment. The strengths of the solutions used ordinarilywill be from five per cent. to ten per cent., no precise generaldirections being practicable, however, since in this matter the processdepends as well upon the kind and condition of the wood treated.

This process is particularly valuable in preserving railroad-ties, andin Fig. 2 is shown in cross-section a tie after being subjected to myabove-described process, as well as a similar view of a board likewisetreated. Each will be found to have a central portion in thoroughlyimpregnated with the preservative zinc chlorid and an external Zone orpermeating-crust y of insoluble zinc silicate. This latterviz., theprotective crust of zinc silicate is of course perfectly insoluble,impervious to water, and relatively unaffected by fire or extremes ofheat and cold and the attacks of insects. Hence it forms an idealprotection for the body of wood inclosed thereby.

Having now described my invention, I make claim to the following:

1. Theherein-described process for treating wood, consisting ineffecting its thorough impregnation with zinc chlorid and thereaftersubjecting the wood to the action of a soluble silicate, preferablysodium silicate, whereby a layer or superficial crust of zinc silicateis formed in the exterior portions of the wood, substantially as setforth.

2. The process substantially as herein described, for preservingrailroad-ties and the like, which consists in effecting the thoroughimpregnation of the wood with a Zinc-chlorid solution by means both ofvacuum and high pressure, and then subjecting said wood to a solution ofa soluble silicate, preferably sodium silicate, under pressure wherebyzinc silicate is precipitated-in the pores of'the wood to a moderatedepth.

3. The product of the herein described process, comprising wood, such asrailroadtics, thoroughly impregnated substantially throughout itsinterior with zinc chlorid, and its exterior portions permeated with aprotective layer of Zinc silicate, substantially as set forth.

Signed by me at Cleveland, Ohio, in the presence of two subscribingwitnesses, this 26th day of May, A. D. 1902.

IENS P. LIHME.

Witnesses:

GEORGE B. RILEY, ALBERT LYNN LAWRENCE.

